This high-octane thriller from Howard (Waterfell) centers on Riven, a 17-year-old Legion General from Neospes, an alternate Earth that was nearly destroyed by warfare centuries earlier. She has come to Earth to find Caden—the handsome, long-exiled twin brother of Prince Cale, who is fighting for his life against a usurper. After months of searching, masquerading as an American teen, Riven enrolls in Caden’s high school just in time to prevent him from being captured by the usurper’s monstrous dead warriors, the Vectors. In the process, Riven discovers that Caden, who doesn’t know who he truly is, has had other defenders, including Riven’s estranged older sister. Soon they’re all on the run with the Vectors in pursuit. The action never stops, and though the language is occasionally over-the-top (“Everything inside of me feels like it’s on fire. My ribs are splintering with alternating bands of hot and cold surging like rotating tides inside me”), SF and dystopia fans will be right at home with this book and its fierce, capable heroine. Ages 14–up. Agent: Liza Fleissig, Liza Royce Agency. (Jan.)